(a) Field of the Invention
The present invention is related to a high-speed digital transmission signal line, and more particularly, to one providing better dynamic resistance.
(b) Description of the Prior Art
As illustrated in FIG. 1 of the accompanying drawings, since the signal communication amount between a liquid crystal display and a main unit in a Low voltage Differential Signal (LVDS) transmission system is extremely enormous and operates at a very high frequency, an LVDS receiver 4 of ultra high-speed (1.4 Gb/s), low power consumption, and low voltage electromagnetic radiation is adapted in an HF (High Frequency) signal transmission system mounted between an LCD interface 2 and a system motherboard interface 3, to serve as a signal transmission interface for the LED interface 2. LVDS receiver 4 is connected by means of a transmission line 5 to complete signal connection with a signal transmission interface on the system motherboard interface 3, i.e., a connector socket 31 disposed on thereon, thus to form an LVDS signal transmission system of the prior art.
However, according to the LVDS interface standard defined in ANSI-YUA-EIA-644-1995, the signal transmission line 5 used in the LVDS signal transmission system must a dynamic resistance Z0 of 100Ω±5% so to match the circuit resistance (Z) of the motherboard interface 3 of the system. Moreover the LVDS signal transmission system must satisfy this condition before the system is capable of achieving EMI and noise reduction and correctly execute the signal transmission between the LCD interface (LVDS interface) 2 and the motherboard interface 3 of the system to prevent errors; otherwise, the signal transmission between the LCD interface 2 and the system motherboard interface 3 will generate signal reflection and noise interface resulting in signal loss, deformation and distortion. “Dynamic Resistance 100Ω” on items 2 and 3 indicate the electronic property of dynamic resistance of both sides of the interface are set at 100Ω to comply with the LVDS standard.
At present, the signal transmission line 5 adapted in the LVDS signal transmission system of the prior art is made of a conventional wire cable, a flexible printed circuit (FPC), or a mini coaxial cable designed with a dynamic resistance Z0 of 100Ω±5%; however, flexible flat cables generally available in the market of comparatively simple construction and lower unit cost are not applicable for use in the LVDS signal transmission system of the prior art since their dynamic resistances Z0 are all approximately at 130Ω, which fails to meet standard operation specifications of the LVDS signal transmission system.